The present invention relates to an actuated film display device.
In large display devices and portable display devices, it has recently been desired that the power consumption is lowered. As the display device attaining the low power consumption, known is an actuated film display device using a movable film shutter in which a movable film is driven by an electrostatic force.
The fundamental structure of the actuated film display device is disclosed in Japanese Patent Application Publication No. 11-95693 (U.S. Pat. No. 6,239,777 B1), the contents of which are incorporated herein by reference. In this disclosure, gray scale display is attained by selectively driving sub pixels constituting one pixel. However, for the gray scale display in the actuated film display device mentioned above, a large number of signal lines and scanning lines are required when a plurality of sub pixels of one pixel are selectively turned on and off. To drive the signal lines and scanning lines, a large number of driving ICs are required. Furthermore, since a plurality of driving ICs are arranged in the display device, the size of the device is inevitably enlarged. In the circumstances, an actuated film display device capable of displaying the gray scale in a simple structure has been desired.
An object of the present invention is to provide an actuated film display device capable of displaying gray scale by a simple driving circuit.
To attain the object, there is provided an actuated film display device according to a first aspect of the present invention comprising:
a first fixed electrode;
a first movable film electrode, which is placed to face the first fixed electrode to form a first optical path on an opposing side to the first fixed electrode, and which has a fixed end and a movable end, the movable end being displaced toward the first fixed electrode by application of a first potential difference between the first fixed electrode and the first movable film electrode, thereby shutting off the first optical path;
a second fixed electrode placed at a predetermined distance from the first fixed electrode; and
a second movable film electrode, which is placed to face the second fixed electrode to form a second optical path on an opposing side to the second fixed electrode, which has a fixed end and a movable end, the movable end being displaced toward the second fixed electrode by application of a second potential difference different from the first potential difference between the second fixed electrode and the second movable film electrode, thereby shutting off the second optical path.
The actuated film display device is desirably constituted as follows:
A distance between the fixed end and the movable end of the first movable film electrode differs from a distance between the fixed end and the movable end of the second movable film electrode.
A thickness of the first movable film electrode differs from a thickness of the second movable film electrode.
A distance between the first fixed electrode and the fixed end of the first movable film electrode differs from a distance between the second fixed electrode and the fixed end of the second movable film electrode.
The display device further comprises a plurality of pixels, each pixel including a pair of the first fixed electrode and the first movable film electrode and a pair of the second fixed electrode and the second movable film electrode.
Each of the first and second fixed electrodes comprises a light guiding portion which is formed of a transparent material and has a curved surface which faces a corresponding one of the first and second movable film electrodes, and an electrode formed of a transparent conductive layer and formed on the curved surface.
The display device further comprises an insulating layer covering the conductive layer.
The first and second fixed electrodes are plate-form electrodes each of which faces a corresponding one of the first and second movable film electrodes so as to form a light guiding portion therebetween.
The display device further comprises an insulating layer covering at least a tip portion of each of the first and second fixed electrodes.
The display device further comprises a light source arranged at a side of the fixed end of the movable film electrode.
According to a second aspect of the present invention, there is provided an actuated film display device comprising:
a fixed electrode formed by insulatively stacking a plurality of conductive layers different in length, in order of length, while the conductive layers are trued up at one end;
a light-shield movable film electrode, which is placed so as to face a surface of the fixed electrode having the shortest one of the conductive layers formed thereon, and which has a fixed end fixed at the one end of the conductive layers and a movable end; and
a potential supply circuit for supplying different potentials to the conductive layers of the fixed electrode, respectively.
According to a third aspect of the present invention, there is provided an actuated film display device comprising:
a plurality of optical shutter sets arranged in rows and columns, each of the optical shutter set comprising at least two optical shutter units different in applied voltage/displacement characteristics, each of the at least two optical shutter units being formed of a fixed electrode and a light-shield cantilever-type movable film electrode fixed at one end; and
a first driving circuit for supplying a driving signal to the optical shutter sets arranged in each of the rows; and
a second driving circuit for supplying a driving signal to the optical shutter sets arranged in each of the columns;
wherein the first driving circuit supplies a first potential to the fixed electrode of the optical shutter units in each of the rows; and
the second driving circuit supplies a second potential to the movable film electrode of the optical shutter units in each of the columns.
According to the present invention, the gray scale can be displayed by the movable film display device without using numerous signal lines and scanning lines. Therefore, it is not necessary to use a large number of driving ICs for driving the numerous signal line and scanning lines. As a result, cost can be reduced. Furthermore, the display device can be reduced in size.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.